When Spells Call for Lemons (Uncollected Anthology: Magical Research Gone Wrong 37)

Reading an ancient book in her university's library, Mae discovers that the original rain spell called for lemon juice rather than purified water. Together with a friend, she decides to attempt the spell using lemon juice instead. Not only does the rain fall harder than expected, but it appears that it's imbued with magic. And that magic is seeping into the ground. Suddenly, the local animals are suddenly able to use magic.
Rats can turn invisible. Crows can talk! Given the location of the university, Mae worries about bears and big cats. She and the other professors must find a way to stop the spread of this magic and return the property to what it once was before something even worse happens!